1. Field of the Invention
The present invention relates to a hydro-dynamic fluid bearing comprising bearing members subject to progressive pre-loading as the rotational speed of an associated shaft increases.
2. Summary of the Prior Art
Hydro-dynamic bearing assemblies are known of which the bearing members are subject to a constant pre-load or the hydrostatic bearing members of which the load can be adjusted. FR-A 2 116 141 relates to a hydrostatic bearing of the latter type according to which when stationary and at low speeds a light pre-load is produced solely by a spring while, when the rotational speed increases, the loading on the bearing member is automatically increased by means of an external fluid. In contrast, in accordance with the present invention, a hydro-dynamic bearing includes provision for progressive loading of the bearing members by making use of fluid under pressure bled from the fluid film lying beneath the bearing member itself. In practice, when the shaft reaches high speed rotation, it entrains the fluid which is interposed between the bearing members and the shaft, thus forming a lubricating film. Further, in accordance with the present invention, at least one of the bearing members is subject when the shaft is stopped to the action of a resilient member producing a pre-load limited strictly to that which is necessary for maintaining the assembly parts in correct relationship, the said resilient means being subject during operation of the shaft to the action of pressure fluid bled from the fluid film under pressure lying beneath the bearing member and so that the load on the bearing member increases with the pressure of the fluid film.